Safety pressure relief and indicating apparatus



Sept. 2, 1930. J. D. HILLIIARD SAFETY PRESSURE RELIEF AND INDICA'IING APPARATUS Filed June-.10, 1929 Inventor John D. HLLLLar'cL,

HLS Attorney.

Patented Sept. 2, 1930 UNITED STATES PATENT, oer-ice Ion D. mmann, OIFCHENEC'L'ADY, NEW YORK, ASSIGNOR '10 GENERAL ELECTBIC comm, A COBPOBATIOR 01 NEW YORK SAFETY PRESSURE mm AND INDIGATDTG APPARATUQ Application fled June 10,

My invention relates to pressure relief apparatus for closed casings which are adapted to contain electrical a paratus and in which pressures may be prodiiced through accident '8 or otherwise suflicient to cause the rupturing of the casing. It is the object of my invention to 'provide an improved apparatus of this character including means for giving an indication when the apparatus has functioned. I'have chosen to illustrate my invention as applied to an oil switch but it is to be understood that its use is not restricted to such for it is equally applicable to other forms of enclosed electrical apparatus, such, for example, as oil immersed transformers.

My invention will be better understood from the following description taken in connection with the accomfianying drawing, and. its scope will be pointe out in theappended claims.

Referring to the 'drawin Fig. 1 is an exterior view of a portion 0 y of an oil switch provided with a-safety pressure relief device embodying myinvention' Fi 2 and3 are cross-sectional views of t e evice taken at right angles to each other; and Fig. 4 illustrates a modification.

The contacts and 0 rating mechanism therefor of' the oil switc shown in Fig. 1 are arranged in a-closed cas' comprising the tank 1 to which is bolted the to 2 sup rt mg the insulator bushings 3 ande mec anism housing 4. These casings are not hermet callyseaied but in cases are provided with a discharge opening with which connects a cooling and se arating device whereb the hot gas formed by the'disintegration o the oil ma be cooled and separated from oil carried ,a ong with it before it is discharged from the casing. In other cases the casing is constructed pressuret except for a small bleed hole through which the gas can gradually escape and the inside and out-become equalized. long 'as the switch functions in the normal manner and is not uired to interrupt circuits beyond its norm-int the flange 1m. semi no. aeaeoa.

nism become deranged so that a sustained arc occurs in the casing a pressure may soon be' developed in the casing suflicient to rupture it. In the copending application of William K. Rankin, Serial No. 204,687, filed July 11, 1927, and in my copending application, Serial No. 204,674, filed July 11, 1927, both assigned to the same assignee as the present application, there are disclosed and claimed safety relief devices of the nature of that shown herein and over which one feature of the present invention is an improvement.

The top 2 of the switch illustrated in Fig. 1 has an emergency relief opening of generous proportions surrounded by the integral upstanding flange 6. To this flange there is secured the end flange of the discharge pipe 7 which may lead directly to a point where hot gas and oil can do no harm or may connect with the header 8 common to a number of switches, which header leads preferably to such a point. Between the pipe 7 and 6 and secured'thereto by throughbOlts is the safet pressure relief ap aratus 10 shown more '0 early in Figs. 2 an; 3. In

. the form illustrated it comprises the supportmg member 11 hav' a. circular 0 mg. therethrough into wh i ri extends the s allow annular flange 12. Clamped againstopposite sides of this flange are the two concavoconvex diaphragms 14 and 15 which preferabl are constructed of thin sheet metal, suc for example, as copper thoroughly annealed and havin a spherical form." For the best results eaci diaphra should make a snug fit in the opening 0 the supporting member and should ma e contact throughout its periphery with the side of the flange 12. The two dlaphragms, as shown in Fig. 3, are arranged with their concave sides to-' ward each other and are clamped against the flange 12 by the small central bolt 16. It is not necessary that the diaphragms make a gas-tight joint with the supporting member and the clamping means which I have shown forms a convenient means of quickly re-' placing new diaphragms for those blown out and does not interfere in the least with the free action of either diaphragm when an ex- 08.88 pressure on its convex ace causes it to collapse and to be blown bodily from the support. If the discharge pipe 7 exhausts independently of any other switch, a single diaphragm only, positioned withits convex face toward the switch is necessary but when a plurality of switches discharge into a common receptacle or header, such as shownin Fig. 1, it becomesadvisable to use a second diaphragm positioned with its convex face toward the header to prevent the first diapragm from being blown out of position by pressure which backs up the discharge pipe upon the discharge into the header of a companion switch. Inasmuch as the diaphragms of this relief device are entirely concealed from view it is possible for the device to function without the switch attendant being aware of the fact. Since an operation of the device is probably the result of trouble in the switch the operator should be immediately notified in order that the switch may be examined and also to replace the blownout diaphragms.

Between the two diaphragms, as shown in Figs. 1 and-2, and extending across the opening in the support I have placed the frangible rod 18, for example, of glass, so as to be struck and carried away by the diaphragms when they are blown out. The rod may be supported in any suitable manner. To facilitate its replacement I have shown by way of example the screw plug 19 having a recess for one end of the rod threaded mto one side of the supporting member. At the opposite side of the member the rod is guided by the screw 20 forming with the member a stufiing box. Attached to the supporting member I have' shown the block- 21 of insulation to which is secured the s ring 22 bearing against the end of rod18. ttached also to the supporting member is another block 23 of insulation to which is attached a the contact 24 which ispositioned to be engaged by the spring 22 when the latter isnot' restrained by the rod 18. Any suitable indicating device may be connected in circuit with members 22. and 24, such, for example, as the bell 25. If desired this circuit may also include suitable apparatus, not shown,for rendering the control circuit of the switch inoperative so as to prevent any closing of the switch if it is already open. As long as the diaphragms and frangi le rod are in place the contacts shown in Fig. 2 are held apart but as soon as thediaphragms are blown out, carrying away the rod with them, spring contact 22 closes the circuitand an alarm is given. Inasmuch as it is more desirable that the bolt 16 be mounted at the center of the diaphragms than that the frangible rod should pass the center thereof, I referably arrange the holes for rod 16 at t e centers of the diaphragms and slightly offset the rod 18 so as not to interfere with the tie bolt. It is obvious that the contacts may if desired be arranged to open instead of close the indicator circuit to cause the operation of the indicating device.

\ In the modified form of my invention illustrated by Fig. 4 the rod 18 is replaced by the wire 27 of easily broken conducting material, such, for example, as fuse metal. This wire preferably is supported in a tube 28 of frangible material, such as glass or hard rubber, where it passes the opening in the supporting member although it may, if desired, be left unsupported. In this arrangement the tie bolt 16 is offset with respect to the centers of the diaphragms. It is, of course, apparent that the tube 28 containin the easily broken wire 27 may be suitably offset with respect to the centers of the diaphragms, if desired, in the manner illustrated in Fig. 2 so that the tie bolt 16 may be mounted centrally of the diaphragm. The two ends of the wire are shown attached to terminals 29 and 30 suitably secured by insulation to the supporting member 11. In circuit with the terminals 29 and 30 I have shown the winding of the relay 31 which is normally energized and which has back contacts by which a second circuit is closed including the alarm bell 32. In accordance with this form of my invention current normally is flowing through the fuse and the relay winding. When the diaphragms blow out the fuse is broken, opening the circuit and 'deenergizing the relay when the alarm bell is caused to operate.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. Electrical apparatus having a closed casing provided with a safety discharge passage, diaphragm apparatus in said passage comprising a supporting member having an opening therethrough, a diaphragm normally closing said opening and adapted to be blown away by excessive pressure on one side thereof, and a frangible circuit-controlling member arranged in the path of movement of said diaphragm.

2; Electrical apparatus having a closed casing provided with a safety blow-out discharge passage, diaphragm apparatus in said passage comprising a supporting member having an opening therethrough, a blow-out diaphragm normally closing said opening, and a angible circuit-controlling member supported by said member in a position to be broken by the blowing-out of said diaphragm.

3. A closed casing adapted to contain electrical apparatus and having a safety discharge passage, a blow-out diaphragm apparatus in said passage comprising a sup orting member having a circular opening t erein and an internal flange, a concavo-convex diaphragm in the opening with its concave side seated against said flange and a circuit:

controlling frangible member supported by the member and arranged at the concave nal 4. A closed casing containing electrical apparatus immersed in an insulating liquid, means connected with said casing forming a safety discharge passage for excessive pres sure produced therein, blow-out diaphragm apparatus in said passage comprising a concavo-convex disk normally closing the passage and arranged with the convex side toward the casing, an alarm device, and a controlling member therefor arranged on the concave side of said diaphragm and adapted to be struck by the diaphragm when the same is blown out. p

5. A safety blow-out diaphragm device comprising a supporting member having a discharge passage therethrough and an interflange, a pair of concavo-convex diaphragms in said passage arranged with their concave faces toward each other, and a member engaging said diaphragms at their central portions for clamping the same against opposite sides of the flange.

6. A safety blow-out diaphragm device comprising a supportin member having a discharge passage theretlirough and an internal .fiange, a pair of concavo-convex sheet metal diaphragms in said passage arranged with their concave faces toward each other, an adjustable rod engagin said diaphragms at their central portions or clamping the diaphragms against opposite sides of said flange and a circuit controlling member extending across said said diaphragms.

7. Electrical apparatus comprising a closed casing provided with a safet blow-out discharge passage, a blow-out d ia hragm normally closing said opening, sai diaphra ada ted to be blown through said passage y p etermined pressure within said casing, and a circuit-controlling member operatively associated with said blow-out diaphragm and adapted to be actuated to cause a circuit-controlling operation in response to the blowing out of said diaphragm.

In witness whereof, I have hereto set my hand'this sixth day of June, 1929.

JOHN D. HILLIARD.

opening and arranged between 

